This disclosure relates generally to integrated circuits, and in particular but not exclusively, relates to input circuits.
A typical integrated circuit includes input circuits to receive signals from other parts of the integrated circuit and to output them with xe2x80x9crestoredxe2x80x9d voltage levels and the appropriate driving current for the circuitry receiving the output signal of the input circuit. As is well known, a variety of sources may inject noise into the signal received by the input circuit. For example, sources include ringing caused by mismatched output drivers or interconnect impedance, signal cross-coupling, and power supply noise. This noise can cause an input circuit to improperly output the received signal.
One conventional solution to this noise problem is create hysteresis in the input circuit by changing the relative xe2x80x9cstrengthxe2x80x9d of pull-up and pull-down paths in the input circuit, as a function of the logic level of the output signal generated by the input circuit (e.g., a Schmitt trigger circuit). However, this solution tends to be sensitive to process, temperature and voltage (PVT) variations and, further, tends to be relatively slow.